1. Field of the Invention
The present invention relates to a plasma generating method for generating a plasma by inputting a high-frequency signal to a treating chamber through an impedance matching device, and also relates to a plasma apparatus and a semiconductor manufacturing apparatus for subjecting a predetermined treatment to an object by using the plasma generated.
2. Description of the Related Art
Generally, with regard to a plasma apparatus, even when a treating chamber itself has the common structure, the input impedance of the treating chamber changes according to the kind of an object in the treating chamber. Therefore, even if individual matching elements of a matching device body are moved to matching positions predetermined by the experiments or the experiences, there may occur a situation in which the impedance between a high-frequency generating unit and the treating chamber 5 cannot be accurately matched. In this state, a high-frequency signal S is not efficiently fed to the treating chamber, and the plasma may not be ignited. In case the plasma is not ignited, moreover, it becomes difficult to execute the treatment of the object promptly.
Also, when the impedance matching is conducted in the plasma apparatus according to the related art, the individual matching elements have to be moved to the matching positions by making the reflectivity come close to a reference value while repeating the feedback controls to control the positions of the individual matching elements individually. Therefore, the plasma apparatus according to the related art has a problem that it takes a long time to match the impedance. Moreover, the impedance matching actions have been ended at a time when the reflectivity reaches the reference value. This raises a problem that it is difficult to move the individual matching elements to the more complete matching positions although the individual matching elements have those complete positions.